The invention relates generally to microwave heating and drying devices and, more particularly, to waveguide applicators forming exposure chambers through which materials are conveyed and subjected to uniform microwave heating.
In many continuous-flow microwave ovens, a planar product or a bed of material passes through a waveguide applicator in or opposite to the direction of wave propagation. These ovens are typically operated in the TE10 mode to provide a peak in the heating profile across the width of the waveguide applicator midway between its top and bottom walls at product level. This makes it simpler to achieve relatively uniform heating of the product. But TE10-mode applicators are limited in width. Accommodating wide product loads requires a side-by-side arrangement of individual slotted TE10 applicators or a single wide applicator. The side-by-side arrangement is harder to build and service than a single wide applicator, but wide applicators support high order modes, which can be difficult to control. The result is non-uniform heating across the width of the product.
Thus, there is a need for a continuous-flow microwave oven capable of uniformly heating wide product loads.